Clinical Information

Antibodies to glycoprotein carbohydrate determinants are prone to interact with a broad variety of plant and invertebrate allergens. These glycoprotein carbohydrates have therefore been termed cross-reactive carbohydrate determinants (CCD). The MUXF3 carbohydrate epitope obtained from digested pineapple bromelain glycoprotein can be used as a representative epitope marker for assessing the presence of IgE antibodies that interact with CCD. As true allergic sensitization to the pineapple bromelain glycoprotein itself is rare, assessing for the presence IgE antibodies reactive with the bromelain MUXF3 CCD glycoprotein carbohydrate epitope serves as a well-established marker for the determination of the presence of anti-CCD IgE antibodies.

CCD epitopes are widely distributed in plants and invertebrate animals, and antibodies against CCD, such as MUXF2, may be associated with a number of positive IgE antibody tests (cross-reactivity) to many different and unrelated plant allergens, but also to a number of potential invertebrate allergens such as bee/wasp venom, cockroaches, mites, and shellfish. Plant protein allergens that contain CCD epitopes include peanuts, grass, pollen, and latex. The presence of anti-CCD IgE antibodies can hinder assessment of the presence of IgE antibodies to these other plant and invertebrate allergens, as it is not possible to distinguish whether observed reactivity is due to the presence of antibodies specific to other proteins, or is the result of the presence of interfering anti-CCD antibodies. When very broad allergen sensitivity profiles are observed in the course allergy testing, it may be due to the presence of cross-reactive anti-CCD IgE antibodies, although the presence of IgE antibodies to profilin proteins should also be considered.

The degree to which antibodies to CCD may be associated with clinical allergic reaction has not been completely resolved. In general, the presence of cross-reactive antibodies to CCD, such as MUXF3, is not thought to be clinically relevant and does not give rise to symptoms consistent with allergic reaction. However, antibodies to CCD may be linked to clinically relevant allergic reactions in extremely rare cases, including in individuals with celery and tomato allergy.